1. Field of the Invention
The present invention relates generally to wireless communication, and more particularly, to handling voice calls and Internet Protocol (IP) media sessions in a wireless network environment.
2. Description of the Related Art
Generic Access Network (GAN) is a telecommunication system that extends mobile voice, data, and IP Multimedia Subsystem/Session Initiation Protocol (IMS/SIP) applications over IP networks. In GAN, a User Equipment (UE), upon detecting a wireless Local Area Network (LAN) (e.g., a GAN cell), establishes a secure IP connection through a gateway to a server called a GAN controller on the cellular network. On the cellular network, the UE communicates over the air with the base station to servers in the core network of the carrier. An advantageous feature of a GAN system is the ability of the UE to migrate from the IP to cellular coverage. Thus, when the UE moves from a Global System for Mobile Communications (GSM) network to an 802.11 network, it appears to the UE as if the UE is communicating with a different base station.
Today, with operators hosting multiple services and other services being hosted by third parties on the Internet, operators prefer to selectively handover certain IP media sessions to the GAN cell when available.
However, the GAN system does not support simultaneous access across different Radio Access Technologies (RATs) like GSM Enhanced Data Rates for GSM Evolution (EDGE) Radio Access Network (GERAN) and GAN. So, when a GAN cell is detected, the UE attaches to the GAN cell and voice and IP media sessions of the UE are transferred to the GAN. Currently, there is no method for selectively offloading IP media data streams to the GAN while maintaining an ongoing voice call (e.g., circuit switched network calls) on the existing GERAN/Universal Terrestrial Radio Access Network (UTRAN).